Lens accessory holder

ABSTRACT

This disclosure explains a concept for a simple accessory holder. The accessory holder, in one embodiment, comprises a wide band having, at each end, a backwardly extending arm with a detent. The accessory holder is made from a springy material so it will snap onto a shutter housing and be held in place by the detents. It comes off by urging the arms apart slightly so the detents come away from the shutter housing. At the center of the band is a hole with means for retaining a filter, a macro lens, and some other lens accessories over an objective lens located in the shutter housing. In one embodiment, the accessory holder and the lens accessory are an integral article.

O Umted States Patent [1 1 [111 3,747,490

Brandt July 24, 1973 LENS ACCESSORY HOLDER [75] Inventor: Edison R.Brandt, Boca Raton, Fla, Pnmary 'fl'fl 'i MiHoran A ttorney-MichaelBard, Robert F. Peck et'al. [73] Assignee: Polaroid Corporation,Cambridge,

- Mass' 57 ABSTRACT [22] F'led: 1972 This disclosure explains a conceptfor a simple acces- 21] APPL N 246 917 sory holder. The accessoryholder, in one embodiment,

comprises a wide band having, at each end, a backwardly extending armwith a detent. The accessory U.S. Cl. holder is made from a p gymaterial so it p Int. Clonto a Shutter housing and be i place the ofSearch ll, tents. It comes f g g the arms apart so 95,44 the detentscome away from the shutter housing. At the center of the band is a holewith means for retaining a [56] References Cited filter, a macro lens,and some other lens accessories UNITED STATES EN over an objective lenslocated in the shutter housing. In 2,926,577- 3/1960 Albrecht 95/44 oneembodiment, the accessory holder and the lens ac- 3,067,664 12/1962Winslow 95/44 cessory are an integral article. 2,992,805 7/1961 Weldon95/11 x e 2,970,509 M1960 5 Claims, 3 Drawing Figures Barthrufi 88/15PATENTEuJuLwan SHEET 2 OF 2 FIG?) LENS ACCESSORY HOLDER BACKGROUND OFTHE INVENTION The present invention relates to photographic filters andother lens accessories and, in particular, to an article for mountingsuch accessories. In the past, the general practice for mounting lensaccessories has been to make them so they will snap or screw into thebezel of the objective lens. Thispractice usually requires the use ofprecisely made parts, such as finely threaded retaining rings, to insurecompatibility with the objective lens the accessory is attached to.Thus, the accessories and the accessory holders are costly. In somecircumstances, the former solution is not practical for lens accessoriesbecause the objective lens mounting is too compact to provide aconvenient means for attaching the accessory or a holder to it.

' SUMMARY OF THE INvENTIoN An accessory holder, according to theconcepts of this invention, comprises a wide band of a springy materialhaving an arm, with a detent, formed at each end of the band. Thearrangement of parts and the choice of material permit the accessoryholder to snap onto the shutter housing, where it is retained by thedetents, rather than onto the objective lens. In the most general formof this accessory holder, the band is made from a common springmaterial,such as phosphor bronze, and has a hole with a means for retaining adesired accessory positioned in .front of the objective lens. Differentaccessories are fitted into the hole as required. The accessory holdermay be made with an-extension to position an auxiliary accessory overthe photodetector of an automatic exposure system to adjust the exposurecontrol in accordance with any change in exposure induced by the mainaccessory. I a An important part of the present concept is that thespringy material the band is made from can be transparent, for example,polycarbonate plastic or polymethylmethacrylatei Whenthe band'is formedfrom a transparent plastic, the accessory, be it a lens or a filter, canbe made as an integral part of the. accessory holder, e.g., a one-piecemolding. This is particularly advantageous if the accessory holder isformed with the extension, since the auxiliary accessory can also bemolded as an integral part.

Accordingly, an object of the present invention is to provide a simpleobjective lens accessory holder for attaching to a shutter housing.

Another object of the present invention is a holder, for objective lensaccessories, having an extension for positioning an auxiliary accessoryover a photocell associated with an automatic exposure control withinthe shutter housing to adjust the control in accordance with any changein the exposure due to the main accessory.

Yet another object of. the present invention is a lens accessory holdersuitable for fabrication together with the lens accessory itself as anintegral article.

DESCRIPTION OF THE DRAWINGS Other objects and many of the attendantadvantages of the present invention will be better appreciated and saidinvention will be clearly understood by reference to the followingdetailed description when considered in conjunction with theaccompanying drawings illustrating one embodiment of the instantinvention, wherein:

FIG. 1 illustrates one embodiment ofa lens accessory holder attached toa shutter housing;

FIG. 2 illustrates another embodiment of the accessory holder, byitself, as seen from its rear; and

FIG. 3 illustrates a third embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference should be made to FIG.1 showing a first embodiment of an objective lens accessory holder 10,according to the present invention, attached to a shutter housing 12 ofa reflex camera (not shown). In the embodiment illustrated, theaccessory holder 10 and an optical element 14 are formed as a unitaryarticle proportioned so it will snap onto the shutter housing 12.

The shutter housing 12 supports an objective lens 16 in its front wall18. The front wall 18 has a button 20 for releasing a shutter (notshown) located to one side of the objective lens 16 and a window 22 foradmitting light into a photocell (not shown) of an automatic exposurecontrol located to the other side. A fo'cusing knob 24 projects slightlyfrom the top wall 25 of the shutter housing 12 so a photographer canrotate it with his forefinger. He thereby focuses the objective lens 16through a gear train within the shutter housing 12 connecting thefocusing means of the objective lens 16 to the focusing knob 24. On theother side of the shutter housing 12, a trim knob 26 projects slightlyfrom the top wall 25. Turning the trim knob 26 effects small adjustmentsof the automatic exposure control located inside the shutter housing 12.A pair of side walls 28 (only one shown) encloses the ends of theshutter housing 12 providing structural support to it and excludinglight and dirt from it. A socket 29 situated on the top wall 25 receivesa linear flash bulb array (not shown in FIG. 1). The flash bulbs permitthe making of artificially illuminated photographs. The other structureof thereflex camera is not germane to an understanding of the presentinvention and is omitted for the sake of clarity and conciseness in thisspecification.

The accessory holder 10 comprises a band 32 extending the width of theshutter housing 12 and two rearwardly extending arms 34. Each arm 34 hasan inwardly extending detent 36 that snaps behind the rear corner 38 ofthe side wall 28. The band 32, the arms 34, and the detents 38 closelysurround the shutter housing 12 and cling to it by means of thespring-like qualities of the'materials that the accessory holder 10 ismade from. Thus the accessory holder 10 supports itself when attached tothe shutter housing 12. The detents 36 catch the shutter housing 12 bysnapping behind the rear corners 38. Thus, the accessory holder 10 willnot come off the shutter housing 12 unless the arms 34 are intentionallyurged apart to free the detents 36 from exposure control. In the absenceof any adjustment,

when the filter is added photographs will be underexposed because thelight received by the photocell is brighter than the light received bythe objective lens. This is due to the attenuating effect of the filterplaced in front of the objective lens.

A part of the present invention is to provide an extension 40 on theaccessory holder to position a secondary optical element 42 in front ofthe window 22 covering the photocell. If the optical element 14 is afilter, the secondary optical element 42 should have the same tint. Thesecondary optical element 42 affects the light entering the window 22 tothe same degree that the optical element 14 affects light entering theobjective lens 16. Thus, a lens accessory holder 10, with integraloptical elements according to the present invention, automaticallycompensates the automatic exposure control for its effect on theexposure. Note that the band 10 is kept narrow on the button 22s side ofthe shutter housing 12 so it will not interfere with pressing the button22.

The optical element 14 and the secondary optical element 42 often haveidentical properties. Thus, lens accessory holders 10 according to thepresent invention can be advantageously made as integral articles fromtransparent materials. In the instance when the optical element 14 andthe secondary optical element 42, if any, is a filter, the accessoryholder 10 and the optical element(s) l4 (and 42) can be manufacturedfrom a trapsparent material in an integral piece as a single article.The transparent material is tinted in any convenient manner to impartthe desired filtering properties to it. The tinting need not berestricted to the regions of the optical element 14 and the secondaryoptical element 42, but can extend throughout the accessory holder 10article. Tinting the article throughout adds an appealing and pleasingvisual aspect to it. The accessory holder 10 with its integral opticalelement(s) 10 and (and 42) can be made by bending from a flat materialor by molding it directly to its final shape by wellknown industrialmethods.

The optical element 14 of the present invention can serve otherphotographic functions in addition to or instead of filtering theincident light. By curving the front and/or rear surfaces of the opticalelement 14, refractive power can be imparted to it. In this manner, aclose-up attachment for use in conjunction with the objective lens 16can be provided to take one-to-one photographs of small objects. Likeways other curvatures on the surfaces of the optical element 14 resultin a wide angle auxiliary lens for use in conjunction with the objectivelens 16. From the preceding description, it is clear that the accessoryholder 10 and an optical element I4, having positive or negativerefractive power, can be formed integrally as a molded'article from atransparent material. It follows, too, that filtering properties canalso be molded into the article so the optical element 14 will bothfilter and refract any incident light.

In some situations, any refractive power provided in the optical element14 will change the cameras field of view significantly enough to effectthe overall exposure level. If experience or analysis indicates that thefield of view of the automatic exposure control should be modifiedaccordingly to compensate for the change in exposure. appropriaterefractive power can be provided on the secondary optical element 42 toaffect the required change.

A preferred material for manufacturing lens acces sory holders 10 withthe integral optical element(s) l4 (and 42) as a unitary article ispolycarbonate plastic. One suitable type is sold under the trademarkLexan by the General Electric company. This plastic is transparent,quite strong, and possesses sufficient elasticity to provide thespring-like action required of the arms 34. Integral lens accessoryholders 10 could also be made from polymethyl methacrylate andpolystyrene.

By using a material with sufficient elasticity, such as polycarbonateplastic, and properly proportioning the cross-sections of the band 32and its arms 34 in relation to their length, the accessory holder 10will attain sufficient springiness to be self-retaining on the shutterhousing 12 when it is dimensioned to fit closely thereto. The accessoryholder 10 can be clipped into place by pressing it against the shutterhousing 12 causing the arms 34 to spread until the detents 36 will slidepast the sides 38 and then snap into engagement with the rear corners38. One simple way to remove the lens accessory holder 10 from theshutter housing is to manually spread the arms 34 apart until thedetents 36 disengage from the rear corners 38. The lens accessory holder10 will then slide forward easily to come off the shutter housing.

Reference should now be had to FIG. 2 illustrating an alternativeembodiment of the present invention. The alternate embodiment comprisesa lens accessory holder 60, a separate lens accessory 62, and a retainer64 to hold the lens accessory 62 in the holder 60. The lens accessoryholder 60 includes a wide band 66 having an arm 68 at each side. Eacharm 68 carriers an inwardly directed detent 70 at the end. As in thepreviously described embodiment, the band 66, the arms 68, and thedetents 70 are arranged to fit closely about a shutter housing (notshown in FIG. 2). The band 66 has a hole in it for receivinginterchangeable lens accessories. The hole is positioned on the band 66so it will align with an objective lens when the lens accessory holder60 is fitted onto a shutter housing. In this embodiment, the band 66 canbe made from opaque materials, such as phosphor bronze spring stock, aswell as transparent ones. The spring qualities inherent in the selectedmaterial retain the lens accessory holder 60 on the shutter housingafter it is snapped in place over the objective lens.

The retainer 64 includes two rings 72, 74 threaded so as to engage oneanother. Each ring 72, 74 has an outward and an inward flange. Theoutward flanges grasp the holder 66 and the inner flanges grasp theaccessory 62 when they are screwed together tightly, thereby rctainingthe lens accessory 62 in the holder 60. Except as described, thisembodiment of the invention functions substantially the same way as theembodiment described above. However, this embodiment has the advantageof accepting interchangeable lens accessories. It will be clear from thedescription of the embodiment shown in FIG. I that the holder 60 couldbe provided with an extension (not shown in FIG. 2) to position asecondary accessory in front of a photocell window on a shutter housing.

A third embodiment, illustrated in FIG. 3, is particularly suited formaking close-up photographs of shiny objects and copies of photographs.In copying photographs or photographing shiny objects, specularreflections (highlights) can create veiling glare, thereby obscuringdesired details.

The accessory holder 98 of FIG. 3 comprises a lateral band 100,extending the width ofa shutter housing 102, with a pair of rearwardlyextending arms 104 attached to and integral with the oppositeextremities of the band 100 and a pair of detents 106 extending inwardlyfrom the ends of the arms 104 so as to engage the rear corners 108 ofthe shutter housing 102.

An opening in the band 100, located in front of the objective lens (notvisible in FIG. 3), receives an auxiliary lens 110, for making close-upphotographs in conjunction with the objective lens, as well as filter112. The filter 112 comprises a linear polarizing element having apolarization azimuth (transmission axis) 114 oriented as indicated. Theauxiliary lens 110 and the filter 112 are kept in place within theopening by a retainer 116.

To compensate the automatic exposure control situate within the shutterhousing 102, for the effect of the filter 112 on the cameras exposure,an extension 118 positions an auxiliary filter. 120 in front of thephotocell (not visible in FIG. 3) of the automatic exposure control. Theproperties of the auxiliary filter 120 that affect light are preferablythe same as those of the filter 112 and the polarization aximuth 122 ofthe former is preferably parallel to that of'the latter.

Situated above the main portion of the accessory holder 98 and in frontof a flash bulb array plugged into the shutter housing 102 is a flashfilter 126. The flash filter 126 comprises a frame 128 attached to theband 100 by a vertical extension 130.

A polarizing filter 132, held in the frame 128, has its polarizationaxis 134 orthogonal to the polarization axis 114. Thefilter 132polarizes the illumination emanating from the flash array 124 before itreaches an object in the cameras field of view. A Fresnel lens 136 orother means held in the frame 128 directs the illuminationemanating fromthe flash array 124 downwards to compensate for the effect of parallaxwhen illuminating nearby objects.

Only linearly polarized light reaches the object to be photographedbecause of the filter 132. Light diffusely reflected by the objecttoward the objective lens will be substantially depolarized, or at leastnot linearly polarized, while light specularly reflected from shinyareas of the object will not have its state of polarization effected.The polarization azimuth 114 of the filter 112 in front of the objectivelens is crossed with respect to the polarization azimuth of theillumination falling on the object. Thus, virtually none of thepolarized light specularly reflected from the object will reach theobjective lens, while approximately half the diffusely reflecteddepolarized light incident on the filter 112 will reach the objectivelens. Those skilled in the photographic art will understand that thisresults in a toning down or elimination of objectionable specularreflections otherwise present in the image of a shiny'object.

The embodiment shown in FIG. 3 is useful in any situation when onewishes to affect the illumination from the flash array 124 before itfalls on the object. It will be understood, therefore, that otheroptical elements besides polarizers and lenses can be used in theaccessory holder 98.

It can be readily seen that many variations and modifications of thepresent invention are possible in light of the aforementioned teachings,and it will be apparent to those skilled in the art that various changesin form and arrangement of components may be made to suit requirementswithout departing from the spirit and scope of the invention. It is,therefore, to be understood that within the scope of the appendedclaims, the instant invention may be practised in a manner thanotherwise specifically described herein.

What is claimed is:

1. A lens accessory, for a photographic camera, adapted for clippingonto the shutter housing of a camera so as to be situate in front of anobjective lens mounted in said shutter housing, said lens accessorycomprising:

optical means for affecting light incident thereon;

a lateral band, integral with said optical means, ex-

tending the width of said shutter housing;

a pair of rearwardly extending arms, each of said arms attached to andintegral with opposite extremities of said lateral band;

a pair of inwardly extending detents, each of said detents attached toand integral with a different one of said arms, said lateral band, saidarms, and said detents fitting closely about said shutter housing andproportioned so said detents engage portions of said shutter housing,whereby said lens accessory attaches to said shutter housing andpositions said optical means in front of said objective lens;

auxiliary optical means for affecting light directed toward a photocellof an automatic exposure control within said shutter housingproportionally to the effect of said optical means on light enteringsaid objective lens; and

extension means, integral with both said lateral band and said auxiliaryoptical means, for positioning said auxiliary optical means in front ofsaid photocell.

2. The lens accessory described in claim 1, wherein it is made from atransparent and resilient material as a unitary article.

3. The lens accessory described in claim 2, wherein said optical meansis a light filter.

4. The lens accessory described in claim 2, wherein said optical meansis an auxiliary lens for said objective lens.

5. The lens accessory holder described in claim 1, further comprisingmeans, attached to said band, for positioning an optical element infront of a flash bulb surmounted on said shutter housing.

1. A lens accessory, for a photographic camera, adapted for clippingonto the shutter housing of a camera so as to be situate in front of anobjective lens mounted in said shutter housing, said lens accessorycomprising: optical means for affecting light incident thereon; alateral band, integral with said optical means, extending the width ofsaid shutter housing; a pair of rearwardly extending arms, each of saidarms attached to and integral with opposite extremities of said lateralband; a pair of inwardly extending detents, each of said detentsattached to and integral with a different one of said arms, said lateralband, said arms, and said detents fitting closely about said shutterhousing and proportioned so said detents engage portions of said shutterhousing, whereby said lens accessory attaches to said shutter housingand positions said optical means in front of said objective lens;auxiliary optical means for affecting light directed toward a photocellof an automatic exposure control within said shutter housingproportionally to the effect of said optical means on light enteringsaid objective lens; and extension means, integral with both saidlateral band and said auxiliary optical means, for positioning saidauxiliary optical means in front of said photocell.
 2. The lensaccessory described in claim 1, wherein it Is made from a transparentand resilient material as a unitary article.
 3. The lens accessorydescribed in claim 2, wherein said optical means is a light filter. 4.The lens accessory described in claim 2, wherein said optical means isan auxiliary lens for said objective lens.
 5. The lens accessory holderdescribed in claim 1, further comprising means, attached to said band,for positioning an optical element in front of a flash bulb surmountedon said shutter housing.